I have created a table but forgot to create an association for foreign key in sequelize.
Now I want to update a column to set as a foreign key..
Can we do that in sequelize?
Related
I have a lot of Foreign Key Columns with cascade delete set to NO ACTION in some specific Schema and I want to Set the FK Columns to ON DELETE SET NULL (for Example) where Primary Key Column's Schema relating to this Foreign Key Column is starting with 'Store'.
I found this article in stack overflow SQL Script to alter ALL Foreign Keys to add ON DELETE CASCADE but unfortunately I was unable to edit it to fit my needs, can somebody help...
I have a requirement of deleting records from the Postgres database tables.
We have a Customer table which is the main table, this table contains a primary key which is used in so many other tables as a FOREIGN KEY, I want to delete one of the customers as well as its reference used in other tables. Is there any way to delete the customer from main table as well as from other tables which contains foreign key.
Thanks in Advance.
In the other tables, you want a cascading delete foreign key reference. You can create one in the database using:
alter table othertable add constraint fk_othertable_customerid
foreign key (customerid) references customers(customerid)
on delete cascade;
Note: This assumes that customerid is the name of the column in both tables and that it is already defined in the other tables.
A cascading foreign key constraint does exactly what you specify. When a row is deleted in the reference table, then all related rows are deleted.
If you already have foreign key constraints on customerid, then drop the existing constraint and add the cascading version.
Is it possible to create entity to postgres foreign table? Always when I want to create doctrine:migration:diff migration tool generate sql to delete foreign tables becouse the entity isn't created for this table.
Normally when creating constraint between two tables i used to use following script:
ALTER TABLE userVendor
ADD CONSTRAINT myrelation
FOREIGN KEY (DataSource, userId)
REFERENCES user(DataSource, userId)
so userVendor table references user table
Now let's say userVendor becomes association table between two tables. Therefore we have additionally third table called Vendor which has datasource and vendor id as composite key. All of them by the way having composite keys.
How to modify my script to say like (wrong script so far):
ALTER TABLE userVendor
ADD CONSTRAINT myrelation
FOREIGN KEY (DataSource, userId, vendorid)
REFERENCES user(DataSource, userId)
REFERENCES user(DataSource, vendorid)
You'll have to add two foreign key constraints, each referencing one table. It is no problem if a column appears in both constraints.
You will need two ADD CONSTRAINT clauses in your ALTER TABLE statement.
I'm trying to understand On Delete and On Update foreign key functions in Entity Framework.
I have a database first (sqlite) model consisting of two tables:
Control
ID
Name
ControlTypeID
and
ControlType
ID
Name
The foreign key constraints on ControlTypeID are set to "On Delete Set Default" and "On Update Cascade." Default is set to "1" on ControlTypeID
The tables are bound to a datagridview. When I delete a ControlType (say, ID=2) rather than Control.ControlTypeID being set to 1, it is set to null.
Does entity framework not preserve the database foreign key constraint rules when it constructs the entity model?